I can see this as a problem but I don't think changing the chat colour of tour chat will make much difference. It is the tour guides responsibility to answer all questions in the chat and sometimes it is easy to miss these, mainly due to how much stuff they have to focus on during tours e.g. making sure people join the vc, leading them in the correct direction, giving useful information during the tour, answering questions from tour chat and VC. If the colour is changed it might help this issue but it is more to do with the person running said tour.

While we are on this topic of Tour Chat, can someone PLEASE let us see local chat from tour chat? A lot of people use it and don't realize you cannot in fact see local chat when in tour chat, and its a lot easier for people who constantly swap between chats to talk in global, not to mention its easy to forget you have to use a third chat.

I think a more broad approach to chats is required and should be investigated, the concerns raised here are a good base to start from. However from PVP lobby there are similar issues locking you out from chat. I think the chat should allow players themselves to add or remove chats as they please (from which they have the permissions to see them)